U.S. Pat. No. 4,505,015 discloses a roll type stock feed apparatus for advancing strip stock such as the metal strip used to form lead frames for integrated circuit chips, in which the lower roll is mounted for tilting movement at a location intermediate the ends of the lower roll so that the lower roll can rock back and forth as needed to automatically balance the forces applied across the width of the strip. In this prior stock feed apparatus, the tiltable force-balancing roller was not powered and accordingly all tractive force for feeding the strip stock, including accelerating and decelerating the strip stock during intermittent feed, had to be provided by the upper roll.
It is also known, for example as disclosed in U.S. Pat. No. 4,420,107 to provide a roll type stock feed apparatus for intermittently advancing strip stock such as lead frames, in which both rolls are driven in timed relation with each other. However, neither of the rolls in this patent are mounted for tilting movement to automatically balance the forces applied across the width of the strip.